The potential for upset or failure of a Fly By Wire (FBW) aircraft control system due to electromagnetic interference is a source of serious concern. The probability that critical avionics circuitry may be exposed to harmful levels of electromagnetic interference is increased when the shielding effectiveness is degraded. Problems such as intermittent data transmission errors are a common result, but complete system failure(s) may occur. In many applications shielded wires are used to route aircraft control signals from control circuitry in part of the aircraft to another. The integrity of the wire shielding may be critical when the wires may be exposed to hazardous environmental electromagnetic effects such as lightning and High Intensity Radiated Fields (HIRF) Signals. It is therefore desirable that the integrity of shielding on certain wires be non-intrusively tested.